that'll be the day

English

Etymology

Originally referring to a significant day in the future regarded as worth waiting for.

Pronunciation

• (Received Pronunciation) IPA^(key): /ˌðætl̩ biː ðə ˈdeɪ/
• (General American) IPA^(key): /ˌðætl̩ bi ðə ˈdeɪ/

• Audio (General Australian):

  (file)

Phrase

that'll be the day

1. (originally Australia, New Zealand, idiomatic, informal) Said in reply to something that one believes will never happen.

   Synonym: that'll be the frosty Friday

   I’m going to get into work on time today. — That’ll be the day!

Translations

said in reply to something that one believes will never happen

• Finnish: sen päivän kun näkisi
• French: quand les poules auront des dents (fr), c’est pas demain la veille (fr)
• Greek: ζήσε Μάη μου (zíse Mái mou), ζήσε Μάη μου να φας τριφύλλι (el) (zíse Mái mou na fas trifýlli, literally “(of a donkey in winter) live till May and eat clover”)
• Russian: когда́ рак на горе свистнет (ru) (kogdá rak na gore svistnet, literally “when the crayfish will whistle on the mountaintop”)
• Spanish: el día que la vaca vuele

See also

• a cold day in hell
• a week from next Tuesday
• until the cows come home
• when hell freezes over
• when pigs fly